Male piece of the velvet type fastener

ABSTRACT

In the velvet type fastener, each male element of the male piece consists of a stem and a cap laterally expanded at the top thereof, and is composed of compositions of a first and a second polyamide polymers having different melting points. These polymers are formed in crystalline composition in the stem and in amorphous composition in the cap. The stem consists of a core portion formed with the first polymer of lower melting point, and a sheath portion formed with the second polymer having a higher melting point. The cap consists of a core and outer layer portions formed with the first polymer, and an intermediate portion of a second polymer sandwiched therebetween.

United States Patent [1 1 Uraya et al.

[ 1 MALE PIECE OF THE VELVET TYPE FASTENER [75] Inventors: Tohru Uraya,Kobe; Eichi Kudo,

Osaka, both of Japan [73] Assignee: Kanebo, Ltd., Tokyo, Japan [22]Filed: May 22, 1973 [21] Appl. No.: 362,802

[30] Foreign Application Priority Data May 29, 1972 Japan 47-6550l [52]US. Cl 428/92; 24/201 R; 24/204; 24/31 V; 28/72 P; 264/15; 428/99 [51]Int. Cl B296 21/00 [58] Field of Search 161/48, 62-67, 161/175; 139/2,391; 24/201, 204',

[56] References Cited UNITED STATES PATENTS 1607995 9/1971 Chiba 264/l5[4 1 Aug. 19, 1975 1/1974 Billarant [61/62 57 ABSTRACT In the velvettype fastener, each male element of the male piece consists of a stemand a cap laterally expanded at the top thereof, and is composed ofcompo sitions of a first and a second polyamide polymers havingdifferent melting points. These polymers are formed in crystallinecomposition in the stem and in amorphous composition in the cap. Thestem consists of a core portion formed with the first polymer of lowermelting point, and a sheath portion formed with the second polymerhaving a higher melting point. The cap consists of a core and outerlayer portions formed with the first polymer, and an intermediateportion of a second polymer sandwiched therebetween.

2 Claims, 7 Drawing Figures PATENTEB AUG 1 91975 Sl'iEET 1 BF 2PATENTEI] AUG] 9l975 PRIOR ART 0 a I n 0 mm W ////////////Z MALE PIECEOF THE VELVET TYPE FASTENER SUMMARY OF THE INVENTION The presentinvention relates to an improvement of the male piece of the velvet typefastener, particularly it relates to an improvement of the male elementprovided with a laterally expanded cap formed at a top end portion of astem projected upright from a base fabric of the male piece.

It is well known that there are two different kinds of velvet typefasteners. One of them is the fastener disclosed in the US. Pat. No.3,009,235, and the other is the fastener disclosed in the US. Pat. No.3,607,995. In the former fastener, the male piece is provided with aplurality of hook elements for engaging loop elements of the femalepiece, while in the latter fastener, a male element provided with a capformed at the top end portion of a stem is utilized instead of the hookelement. We have found from experience that the latter type of maleelement has a superior engaging function with a loop of a female elementwhen a shearing force is applied between the male piece and the femalepiece, compared to the former male or hook element. As to the materialfor making the male element of the latter fastener, polyolefin orpolyamide monofilament yarn have been preferably utilized, because oftheir desirable properties of elasticity, heat durability and strength,etc. However, from our experiences in practical use, we have found thatthe strength of the connected portion between the cap and the stem ofthe male element is insufficient and, consequently, the cap is apt to bebroken off from the stem after repeated utilization of the fastener.

The principal object of the present invention is to eliminate theabove-mentioned drawback of the velvet type fastener of the latter type.

The characteristic feature and composition of the velvet type fasteneris hereinafter described with reference to the accompanying drawings andclaims.

BRIEF EXPLANATION OF THE DRAWINGS FIG. I is a schematic perspective viewof an embodiment of a male piece according to the present invention;

FIGS. 2A 2D are enlarged side views of the male pieces according tomanufacturing steps of the velvet type fastener of the latter type;

FIG. 3 is an enlarged longitudinal cross sectional view of a maleelement of a conventional fastener of the latter type for the purpose ofcomparison with the present invention;

FIG. 4 is an enlarged longitudinal cross sectional view of a maleelement shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION To find a technical background ofthe present invention, the process for manufacturing the male piece ofthe velvet type fastener of the latter type was firstly analyzed.Referring to FIGS. 1, 2A to 2D, as disclosed in the specification ofU.S. Pat. No. 3,607,995, the male piece is produced by the followingsteps: (1) a double woven fabric, wherein two base fabrics 2 areinterconnected by connecting threads 1 made of monofilament yarn isproduced; (2) the base fabrics 2 are separated each other by cutting theconnecting threads 1 so that each separated base fabric 2 is providedwith a plurality of upright monofilament piece 1 (3) the separated basefabric 2 is coated with a bonding resin so as to fix the uprightmonofilament piece I thereto, consequently material fabric is produced;(4) next, the material fabric is passed through a water bath so as tocool the material, and immediately afterwards the material is carried toa heat treatment process in which the tip of each upright monofilamentpiece is fused by applying heat energy rapidly while the remainingportion thereof is maintained in crystalline composition; (5) after thisheat treatment the material is passed through cool water so as tosolidify the fused portions of the material.

According to the above-mentioned heat treatment, a plurality of maleelements, composed of a stem portion 4a and a fused tip portion 4bthereof, can be formed on the base fabric 2, so that the male piece isproduced as shown in FIG. 3. In the abovementioned manufacturing method,a pile knitted fabric can be utilized instead of the pile woven fabric.

Based on our common technical knowledge, if the synthetic resin materialin crystalline composition is fused, this fused portion 4b has anamorphous composition. Consequently, it may be understood that the fusedportion of the upright monofilament yarn of the male piece has anamorphous composition. As the tip portion is fused, this portion has amushroom type shape expanded laterally. This portion is hereinafterreferred to as a cap 4b, and the remaining upright portion of themonofilament yarn is hereinafter referred to as a stern 4a. As alreadyillustrated, the cap 4b has an amorphous composition while the stem 40has a crystalline composition. It must be understood that, there is notany critical boundary line between these amorphous compositions and thecrystalline compositions. However, in the connecting or boundary portionbetween the stem and the cap, the composition of polyamide polymer isdistinctively changed from the crystalline condition to the amorphouscondition. Therefore, this connecting portion is one of the weak pointsof the male element. To conform the above-mentioned weakness of theboundary portion between the cap 4b and stem 40 of the male element, themicroscopic observation of this portion was carried out. It was foundthat a certain number of male elements are provided with cracks formedin the boundary portion thereof. It may be interpreted that these cracks5 are created according to the difference of heat-shrinkage between thecap and the top portion of the stem, effect of rapid heating and effectof rapid cooling. Therefore, if a strong shearing force is appliedbetween an engaged male piece and female piece the above-mentionedcracks are expanded and finally in a certan number of male elements, thecaps 4b are separated from the stems 40 thereof.

Both theoretical and experimental research has been carried out toeliminate the above-mentioned weak point in the boundary portion of eachmale element. As a result of this research the following very uniquesolution has been established. That is, in the present invention, as amaterial for the pile yarn, a nylon monofilament yarn having aconfiguration of a core portion 6a and a sheath portion 6 covering thecore portion is utilized (FIG. 4). It is important to realize that thecore portion 6a is made of a nylon polymer having a lower melting point,while the sheath portion 6 is made of another nylon polymer having ahigher melting point than that of core portion. Therefore, when theabovementioned heat treatment is applied to the material and the tip ofthe stem is fused, the tip of the core portion 6a and the tip of thesheath portion 6 are fused as shown in FIG. 4. As the melting point ofthe nylon polymer of the core portion 6a is lower than that of thesheath portion 6, the configuration of the cap is composed of a fusedcore portion 6b and outer layer 60 and an intermediate fused portion 6dformed between the core portion 6b and the outer layer 6c. As a resultof our microscopic observations it was confirmed that the core portion6b and the outer layer 60 are formed with a fused nylon polymer of thecore portion 6a of the stem, while the intermediate portion 6d is formedwith a fused nylon polymer of the sheath portion 6. Even if certaincracks 8 are formed in the boundary portion, as the inner terminal ofcracks 8 cannot expand further because of the outer layer 6c, theabovementioned drawback of the conventional fastener of the latter typecan be effectively prevented. The experimental test which is hereinafterexplained, proves this characteristic feature.

As to the polyamide polymer utilized for manufacturing the nylonmonofilament yarn to produce the male element according to the presentinvention, it is preferable to use polycapramide (nylon 6) prepared bythe polycondensation of e-caprolactam or 6-aminocaproic acid, or amixture thereof, polyhexamethylene adipamide (nylon 66), and polymerspolycapramide or polyhexamethylene adipamide for their main ingredientsand having the substantially same characteristics as those ofpolycapramide or polyhexamethylene adipamide, which may comprise one ormore other components copolymerized with the above polymer formingmonomer. These polymers may optionally comprise inorganic or organicmaterials of, for example, delustering agents, pigments, dyes,weather-proofing agents (ultraviolet ray absorbing agents), antistaticagents, plasticizers and flameretardant agents. in the nylonmonofilament yarn, two of these polymers having different melting pointsare used and conjugately spun into sheat-core type yarn. In order toobtain a yarn desirable to the purpose of the present invention, it isdesirable that the difference of the melting point between the polymerscomposing the sheath-core type yarn is more than 20C, preferably from 40to 60C. When the difference of the melting point is less than 20C, it isdifficult to cover the subsequently fused portion with the firstly fusedportion at the time of the heat treatment. On the other hand, when thedifference of the melting point is more than 60C, the cap cannot be inmost cases normally formed, due to the fact that the amount of the fusedpolymer in the firstly fused portion becomes too large for the amount ofthe fused polymer in the subsequently fused portion.

For the two component polymers of the nylon monofilament 6-nylonaccording to the present invention, homopolymers such as nylon 6 andnylon 66 may be used in combination with each other. However, it isdesirable that a known copolymerized nylon is used, as one of thetwo-component polymers, together with the above-mentioned homopolymer,or that polymers bearing therebetween the melting point difference offrom 20 to 60C are selected from the various types of copolymerizedpolyamides and used as the two component polymers. in general. it ispreferable to use low melting point polyamides of a two-component systemsuch as nylon -nylon 66, nylon6-nylon 610, nylon 6- nylon 6T or nylon66-nylon 610, and a threecomponent system such as nylon 6l0-nylon6-nylon 66. These two-component polymers can form the desired capformation sufficient for practical use, if the difference of the meltingpoint therebetween is less than 60C.

For practical utilization of the velvet type fastener according to thepresent invention, a monofilament yarn having a thickness in a range of70 denier i000 denier, preferably 200 denier 800 denier is used. It isrequired to use the drawn monofilament yarn having crystallinecomposition. However, the thicker monofilament may be used according tothe end use of the fastener if the weaving or knitting operation can becarried out. With regard to the cross-sectional shape of themonofilament yam, it is preferable to use a yarn having a circularcross-section wherein the core portion and the sheath portion have aconcentric longitudinal axis.

The occupying ratio (in weight) of the core portion and the sheathportion in the monofilament yarn may be chosen in a range between /2050/50.

Example A monofilament yarn of 300 denier was prepared by using in thesheath portion nylon 6 having a melting point of 2l5C and prepared bypolymerization of e-caprolactam, and in the core portion copolymerizedpolyamide having a melting point of C and consisting of 52 parts ofnylon 6 and 48 parts of nylon 66. The melt spinning was carried out at280C by means of an ejecting nozzle for conjugate spinning ofsheath-core type yarn and the occupying ratio of the sheath portion andthe core portion in the obtained yarn was in 25 75 by weight. Then, theyarn was drawn in a conventional manner.

The above-mentioned monofilament yarn was utilized as a material forpile. A pile fabric was produced under the following conditions.

(e) a pile was formed at each 8 picks in an arrangement of plain weave(f) height of pile 2 mm The above-mentioned pile fabric was supplied toa heat treatment process. In this process, the tip of the upright stemsof the monotilament yarn was exposed to a heater maintained at 350C forl/IO see by carrying the material at a speed of 3 m/min, so that the tipof each upright stem of the monofilament yarn was fused. Consequently,the male elements were formed.

For the sake of comparative testing, two conventional fasteners wereproduced by utilizing 6 nylon monofilament yarn and a polypropylenemonofilament yarn, by applying a similar manner of processing, exceptfor the heat treatment temperature. (350C for the 6 nylon filament, 320for the polypropylene filament). These male elements had theconstruction shown in FIG. 3, respectively. Next, repeated tests of thenumber of engaging and disengaging operations until at least one cap isseparated, were carried out. Further, the resistances againstdisengaging were measured by applying the following tests. That is,after firmly engaging the male piece with the female piece, an end ofthe male piece was pulled upward from the female piece, and the forcewhich was required to separate this end of the male piece from thefemale piece was measured by a spring balance. This resistance isreferred to as a separation resistance (gICm) in the table. Shearingresistance was measured by applying the following measured method. Afterfirmly engaging the male piece with the female piece, a free end of themale piece and a free end of the female piece were gripped by a pair ofgrippers of a tensile test apparatus. In this test, the width of thesample pieces were 2 cm, respectively, the distance between the twogrippers was cm, the length of engaging portion was 2 cm. The forcewhich was required to separate the male piece from the female piece wasmeasured by this tensile test apparatus. A shearing force of kg/cm wasthen calculated from the above-mentioned measured force. Theabovementioned tests were also carried out after the male piece and thefemale piece were engaged and disengaged 3000 times.

6 Nylon Present Invention Example Poly propylene Test Number of repeatedtest until at least one cap is broken 08 Initial condition Peeling testg/cm Shearing force kg/cm After 300 times of engagement anddisengagement Peeling test g/cm Resistance ltg/cm conventional malepiece.

What is claimed is:

1. In a male piece of a velvet type fastener provided with a pluralityof male elements projected upright from a base fabric, an improvementcomprising, each male element made of a synthetic monofilament yarncomposed of a core portion extended along an axis thereof and a sheathportion encircling said core portion, said core portion composed of afirst polyamide polymer of a lower melting point while said sheathportion is composed of a second polyamide polymer of higher meltingpoint in comparison with said first nylon polyamide resin, said maleelement being composed of a stem and a laterally expanded cap'formed ata top end portion of said stem, said cap being composed of a core and anouter layer formed with said first polyamide polymer and an intermediateportion being formed with said second polyamide polymer, the temperaturedifference between said melting points of said first and secondpolyamide polymers being between 40 and C.

2. [n a male piece of a velvet type fastener provided with a pluralityof male elements projected upright from a base fabric, an improvementcomprising, each male element made of a synthetic monofilament yarncomposed of a core portion extended along an axis thereof and a sheathportion encircling said core portion, said core portion composed of afirst polyamide polymer of a lower melting point while said sheathportion is composed of a second polyamide polymer of higher meltingpoint in comparison with said first nylon polyamide resin, said maleelement being composed of a stern and a laterally expanded cap formed ata top end portion of said stem, said cap being composed of a core and anouter layer formed with said first polyamide polymer and an intennediateportion being formed with said second polyamide polymer, the temperaturedifference between said melting points of said first and secondpolyamide polymers being between about 20 and 60C.

1. IN A MALE PIECE OF A VELVET TYPE FASTENER PROVIDED WITH A PLURALITYOF MALE ELEMENTS PROJECTED UPRIGHT FROM A BASE FABRIC, AN IMPROVEMENTCOMPRISING, EACH MALE ELEMENT MADE OF A SENYTHETIC MONOFILAMENT YARNCOMPOSED OF A CORE PORTION EXTENDED ALONG AN AXIS THEREOF AND A SHEATHPORTION ENCIRCLING SAID CORE PORTION, SAID CORE PORTION COMPOSED OF AFIRST POLYAMIDE POLYMER OF A LOWER MELTING POINT WHILE SAID SHEATHPORTION IS COMPOSED OF A SECOND POLYMIDE POLYMER OF HIGHER MELTING POINTIN COMPARISON WITH SAID FIRST NYLON POLYAMIDE RESIN, SAID MALE ELEMENTBEING COMPOSED OF A STEM AND A LATERALLY EXPANDED CAP FORMED AT A TOPEND PORTION OF SAID STEM, SAID CAP BEING COMPOSED OF A CORE AND AN OUTERLAYER FORMED WITH SAID FIRST POLYAMIDE POLYMER AND AN INTERMEDIATEPORTION BEING FORMED WITH SAID SECOND POLYAMIDE POLYMER, THE TEMPERATUREDIFFERNCE BERWEEN SAID MELTING POINTS OF SAID FIRST AND SECOND POLYAMIDEPOLYMERS BEING BETWEEN 40* AND 60*C.
 2. In a male piece of a velvet typefastener provided with a plurality of male elements projected uprightfrom a base fabric, an improvement comprising, each male element made ofa synthetic monofilament yarn composed of a core portion extended alongan axis thereof and a sheath portion encircling said core portion, saidcore portion composed of a first polyamide polymer of a lower meltingpoint while said sheath portion is composed of a second polyamidepolymer of higher melting point in comparison with said first nylonpolyamide resin, said male element being composed of a stem and alaterally expanded cap formed at a top end portion of said stem, saidcap being composed of a core and an outer layer formed with said firstpolyamide polymer and an intermediate portion being formed with saidsecond polyamide polymer, the temperature difference between saidmelting points of said first and second polyamide polymers being betweenabout 20 and 60*C.